This invention relates to an apparatus for the manufacture of sheets or board units from cellulose or fibrous material or wood shavings and comprises a multi opening press for accommodating one or several press plates between which wet sheets or dry sheets supported by the plates or wire cloth frames are subjected to pressure and heat treatment, a conveyor track defining a closed circuit for returning the plates or frames from the discharge side of the press to the feed side thereof and elevator members for displacing the plates or frames in vertical direction between the conveyor track and the compartments located on different levels of the multi opening press or between the compartments and the conveyor track.
In the manufacture of sheets or board units by means of an apparatus of the kind described above it is of greatest importance to maintain a high feeding speed throughout the operation in order to produce the greatest possible number of sheets or board units per unit time. In the use of known apparatuses some delay is experienced in the feeding and discharge of the conveyor or surface plates or frames to or from the elevator members. This is due to the fact that the conveyor track which usually has a rectangular pattern is located in a single plane. Therefore, in order to avoid collision between the plates or frames at the corners of the rectangular track, where they reverse their direction of travel, it becomes necessary to remove the plate or frame entirely before the entrance of a successive plate or frame into the corner. The delay experienced at the respective corner inplies that the respective plate or frame must be moved a distance equal to the width or length of the plate or frame.